A conventional solid state drive (SSD) operates differently than a hard disk drive (HDD). In a HDD, each logical block address (LBA) that a host wants to write has a fixed physical address space for the write operation. In an SSD, there is not an LBA limitation. In a conventional NAND flash, data is written in pages. If one page has been written with data, a new data needs to be written to the page. An erase operation needs to be performed on the block containing the page. After the erase, new data can be written on the page. If the data in some of the pages of the block is no longer needed (also called stale pages), only the pages with valid data in that block are read and re-written into another previously erased empty block. Then the free pages left by not moving the stale data are available for new data. This is called Garbage collection. In a conventional system, Garbage collection needs to be searched from all of the pages of one block, which is time consuming.
It would be desirable to implement a physical-to-logical address map to speed up a recycle operation in SSD.